linux-kernel - Re: [PATCH v7 6/9] interconnect: qcom: rpm: Handle interface clocks

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Message-ID: <0af8ba67-f33c-4861-bea5-e662d19638bf@kernel.org>
Date:   Tue, 21 Mar 2023 15:58:30 +0200
From:   Georgi Djakov <djakov@...nel.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Bryan O'Donoghue <bryan.odonoghue@...aro.org>
Cc:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 6/9] interconnect: qcom: rpm: Handle interface clocks

Hi,

On 11.03.23 17:26, Dmitry Baryshkov wrote:
> On 11/03/2023 16:38, Bryan O'Donoghue wrote:
>> On 11/03/2023 14:35, Dmitry Baryshkov wrote:
>>>> Its probably worthwhile experimenting to see if the*ufs*_clk can/should
>>>> be added to the UFS device list of clocks.
>>> While we were doing this for some of the clocks (PCIe and USB, if I'm
>>> not mistaken), I think that generally this is not fully correct. In my
>>> opinion it should be in the interconnect driver, who turns
>>> corresponding clocks on and off. These clocks correspond to the SoC
>>> topology, rather than the end-device.
>>>
>>
>> True enough, they are interconnect clocks.
>>
>> The question is how to only turn them on when the device that depends on them wants them.
> 
> I think we can turn them on an off from qcom_icc_set(). Each node can list required clocks.
> 

Yes, this is a bit weird, but looks like these are the interface clocks
required for programming the qos box of the respective peripheral and
nothing else. Maybe we can even configure QoS just once (eg. on the first
bandwidth request) and not every time we call qcom_icc_set().

BR,
Georgi